This invention relates to vehicles that derive motion from one or more flapping wings.
One approach to heavier-than-air flight employs flapping wings to generate a combined lift-thrust force. In principle, flapping wing technology offers the possibility of creating versatile flight vehicles that can combine and in some cases exceed the performance advantages of fixed-wing and rotary-wing technologies. In particular, flapping wing technology offers the possibility of providing improved maneuverability compared to even rotary-wing technologies. Vehicles employing flapping wing technologies are referred to as “ornithopters”.
Unfortunately, very few ornithopters have succeeded in flying. In 1929, Lippisch developed a human-powered ornithopter that achieved non-sustained flight. In 1986, MacCready et al. developed an ornithopter modeled on a pterosaur, an extinct flying reptile. That ornithopter was winch launched and could not sustain flight for an extended duration. More recently, Harris and DeLaurier developed an ornithopter that was capable of sustained flight. In addition, various toys have been developed that employ flapping wing technology to fly, including that described in U.S. Pat. No. 4,729,728 to Van Ruymbeke.
Unfortunately, even those previous ornithopters that were capable of flight were very limited in their maneuverability. These ornithopters operated by flapping wings only in a single trajectory, i.e., in an up and down motion. Thus, the aerodynamic force developed by the flapping wings over the course of a series of “beats” was fixed in a fixed (relative to the vehicle), substantially vertical plane. To develop lift, these ornithopters mimicked conventional fixed wing aircraft in that in all cases lift was achieved by creating airflow past an airfoil due to the forward motion of the vehicle as a whole. Thus, these ornithopters suffered from the same maneuverability limitations as conventional fixed-wing aircraft.
In an analogous way, conventional and submersible watercraft, spacecraft and satellites also are limited in their maneuverability due to the design of their propulsion systems.
In U.S. Pat. Nos. 6,206,324 and 6,565,039 and PCT/US00/23544, all to Michael J. C. Smith, a wing-drive mechanism is described, together with methods for controlling the wing-drive mechanism to effect flight. The wing-drive mechanism described in the patents and the applications is capable of independent movement about flap, pitch and yaw axes through the operation of three axis drive mechanisms.
Because of the continual desire to minimize weight in all flying vehicles, it would be desirable to provide a wing-drive mechanism that is strong, durable, light weight, and which operates smoothly and reliably.